Gap detection for similar and dissimilar gap markers

Abstract

Gap detection for acoustic stimuli is most acute for iso-frequency gap markers and becomes poorer when the two markers are shifted apart in frequency. Gap detection for electrical stimuli presented on a single (iso-frequency) electrode channel in cochlear implant users is most acute when the two markers of the gap are perceptually similar and becomes poorer for perceptually dissimilar markers [M. Chatterjee, Q. Fu, and R. V. Shannon, J. Acoust. Soc. Am. 103, 2515–2519 (1998)]. This raises the question of whether the decline in performance for acoustic stimuli with disparate frequencies reflects poor across-frequency temporal processing or the effects of a perceptual discontinuity between the two markers. To test this, gap detection was measured in a group of normal-hearing listeners using markers that were either perceptually similar or dissimilar. The types of markers were pure tones, am tones, and fm tones. The two markers bounding a gap were either the same or differed in type, frequency, and/or modulation rate. Results indicated that gap detection performance declined for frequency-disparate markers but did not uniformly deteriorate for perceptually dissimilar markers. [Work supported by NIH NIDCD R01-DC01507.]